CHART WEEK – Part 5: Tackling and Run Defense

Today, in the final installment of CHART WEEK, we’ll take a look at the IU defense’s tackling and general performance against the run. As a reminder, we’ve aggregated our weekly Film Study charts for the full 2016 season, and each day this week, we will use a few of those charts to learn something about what happened in 2016 and what might happen in 2017. We’ve already covered the pass rush, passing offense, passing defense, and rushing offense.

Like the “pressures” stat that we discussed on Monday, “missed tackles” (“MT” in the chart to the right) is not an official stat. It is based on my own review of each game and is necessarily subjective and imperfect. That being said, I work hard to be consistent in my application of my “missed tackle” standard, which I define1 as a defender making contact with a ball carrier that could conceivably have brought the ballcarrier down, but didn’t. The contact aspect of the definition means that a few obvious misplays where a defender just whiffs entirely avoid characterization as a missed tackle, but I think it is cleaner than trying to guess which defender who didn’t actually make contact might have been able to make a tackle. The “could conceivably have brought the ball carrier down” aspect eliminates situations where a defender merely gets a hand on a passing runner – and therefore technically makes contact – but the contact would never be enough to make the tackle.

On to the substance. First, there’s a clear trend in the tackling percentages: the farther away from the ball a defender lines up, the lower his tackling percentage will be. That makes sense. Defensive linemen – and especially interior defensive linemen – are tackling runners in tight spaces where they generally do not have room to make defenders miss, and D-linemen almost always have a size and strength advantage over the ballcarrier, which generally helps with tackling. On the other end of the spectrum, safeties and corners have to make tackles in space, often at a size or strength disadvantage,2 generally leading to more missed tackles. With that in mind, a few notes about IU’s tackling numbers:

When Ralph Green tackles you, you stay tackled. Big Ralph led the team in tackling percentage3 at 97%, missing just 1 tackle. I miss him already. If you haven’t already, do yourself a favor and watch Ralph talk about EVERYTHING at IU’s Pro Day.4 IU’s other interior D-linemen, Nate Hoff and Mike Barwick, were right on Ralph’s heels at 95%.

Starting linebackers and all around studs Marcus Oliver and Tegray Scales combined for 222 tackles and only 21 missed tackles. An incredible performance by both guys. Looking at Oliver’s possible replacements, in limited duty, Chris Covington was superior to Dameon Willis in terms of tackling percentage, 97% to 81%.

Tony Fields and Marcelino Ball led the team in missed tackles, but in both cases, one bad game set each guy back. Marcelino Ball missed 4 tackles (one-third of his total) against Maryland. Take out that game and Ball’s tackling percentage jumps to 90%. For his part, Fields missed 3 tackles against Michigan5, and without those, his percentage would rise to 89%.

The theory I espoused above about defensive linemen breaks down a bit with IU’s defensive ends. Robert McCray had the worst tackling percentage by a large margin at 62%. Greg Gooch and Nile Sykes were both below 85%. Some of that can be chalked up to small sample size, and it’s reasonable to expect all three to improve in 2017.

I’m kicking myself for not tracking missed tackles in 2014 and 2015. My guess is the 2016 numbers would show massive improvement.

For our final chart of CHART WEEK, here’s a look at how IU’s opponents fared on the ground by direction:

I don’t place much importance on left/right in this chart because IU’s defense aligns based on the offense’s strength. This means that a run to the right from one formation will not face the same defenders as a run to the right from another formation. The inside/outside split is more useful, in that it can indicate a particular schematic strength or weakness of the defense. Here, the IU defense allowed 4.4 yards-per-carry on inside runs, and 4.2 yards-per-carry on outside runs. Ideally, that inside run number would drop below 4.0 in 2017, but that outside run YPC is perfectly acceptable, in that explosive plays are more likely to come on outside runs. If a defense is holding its opponents to just over 4.0 YPC on outside runs, it is doing a good job of limiting long runs to the outside.